4 
A. SMITH WOODWARD 
(Schwed. Südpolar -Exp. 
the reception of the head of a rib, while the base of the neural arch does not ex- 
tend to the front edge of the centrum. Another vertebral centrum is essentially 
similar, but with the short transverse process and the rib-articulation a little higher. 
Fig- 5- — DIctothenia sp.; foremost vertebral centrum, anterior, posterior (a), left lateral (/d, and lower (r) 
views, nat. size. tr. transverse process. 
A rounder and more elongated vertebra has the rib-articulation raised to the base of 
the neural arch. Two caudal vertebral centra, which may well have belonged to the 
same fish, are deeper than wide and exhibit the same texture as the abdominal 
centra just described. 
Explanation of Plate 1. 
Fig. I. Nearly complete vertebral centrum of Ftychodus, from the Cretaceous of Seymour 
Island. I, \ a. end-views; i h. cross-section; i c. edge-view, showing pit {a) 
for base of arch, and the perforation of the laminæ; i d — f. enlarged sections 
of laminæ. 
Fig. 2. Smaller specimen in hard nodule, with (2 a — c) enlarged sections displaying the 
laminar sti'ucture. 
Fig. 3. Smaller specimen in hard nodule, showing flaking of the tissue of the vertebra. 
Fig. 4. Broken Selachian vertebral centrum from the Cretaceous of Bohemia. 
Unless otherwi.se stated, the figures are of the natural size. 
Stockholm. P. A. NorsleJt & Söner 1908, 
